The %PATH% environment variable contains a list of folders. When a command is issued at the CMD prompt, the operating system will first look for an executable file in the current folder, if not found it will scan %PATH% to find it.

Use the PATH command to display or change the list of folders stored in the %PATH% environment variable.

It is important that the pathnames are delimited with semicolons NOT by quotes.
PowerShell in particular will ignore any path node delimited by double quotes.

To view each item on a single line use this:

for %G in ("%path:;=" "%") do @echo %G

Or in a batch file:

for %%G in ("%path:;=" "%") do @echo %%G

To add items to the current path, include %PATH% in your new setting.
For Example:

PATH=%PATH%;C:\Program Files\My Application

Note you do not need to surround each part of the path with double quotes, PATH will automatically treat spaces as part of the filename.

Permanent Changes

Changes made using the PATH command are NOT permanent, they apply to the current CMD prompt only and remain only until the CMD window is closed.

The %PATH% variable is set as both a system and user variable, the 2 values are combined to give the PATH for the currently logged in user. This is explained in full by MS Product Support Article Q100843

Be wary of using commands like SETX to modify the PATH - the User path can be edited, but the System path remains read-only for most users. If you try to delete an old value and add a new one it is very common for the 'delete' to fail and the 'add' to succeed, resulting in duplicate values being added to the path.

If you are trying to modify the path to add settings for a single application, a reasonably safe method is to use a second variable:
e.g.

SetX MYAPP "C:\Program Files\My App" -m

Now include your new variable in the path like so ...C:\Windows\system32;%MYAPP%

You can now easily change that one variable %MYAPP% at any time in the future and the PATH will reflect the new value.

Changing a variable in the Control Panel will not affect any CMD prompt that is already open, only new CMD prompts will get the new setting.

To change a system variable you must have administrator rights

If your system has an AUTOEXEC.BAT file then any PATH setting in AUTOEXEC.BAT will also be appended to the %PATH% environment variable. This is to provide compatibility with old installation routines which need to set the PATH. All other commands in AUTOEXEC.BAT are ignored.

Dpath

DPATH is an undocumented internal utility that allows the TYPE command to read data files in specified directories as if they were in in the current directory. On some OS's this is also implemented as the now deprecated APPEND command. The list of directories is held in the %DPATH% environment variable which works just like the %PATH% variable, delimited with semicolons (not quotes). Syntax: DPATH pathname [;pathname]...